Niall Carson - WPA Pool / Getty Images(LONDON) -- The happy news of Kate Middleton's pregnancy brings with it a flurry of questions, one of the hottest being whether the baby is a boy or a girl -- a fact that could have historical significance, as the rules of royal succession are on the cusp of changing.

On Monday, representatives from St. James Palace officially announced that their Royal Highnesses, the Duke and Duchess of Cambridge, are expecting a baby. And because of proposed changes in rules that came late last year, it is anticipated that -- boy or girl -- the child can eventually succeed to the throne.

The reforms were first announced in October 2011 by Prime Minister David Cameron during a visit to Australia. Cameron said the constitutional changes to remove male preference in succession had been agreed upon by the commonwealth nations.

The change means that if Middleton gives birth to a girl, the child will take precedence over younger brothers in the line of succession and will become monarch.

Although U.K. legislation has not yet been passed to change the existing succession laws, in May the queen confirmed at the opening of Parliament that the British government would work with commonwealth countries to bring in a new royal succession law. It is understood that proposed legislation would apply to descendants of the current Prince of Wales, Charles, Prince William's father.

U.K. legislation will be introduced once 14 of the 16 commonwealth nations have agreed to change their laws.

The rules, as they stood until last year, not only gave boys precedence over girls when it came to the monarchy but also prevented future monarchs from marrying Catholics.

"[The change] brings the British monarchy into line with other European monarchies," Carolyn Harris, a teaching fellow and royal historian at Queen's University in Ontario, Canada, told ABC News.

When the U.K. moved to change its rules, it followed several of its neighboring countries, who over the past few decades had made such reforms. The Swedish Parliament had made the change to oldest child in 1980, whether a boy or a girl, in the interest of gender equality -- despite the king's protest. The Netherlands followed suit in 1983, Norway in 1990, Belgium in 1991 and Denmark in 2009.

The new succession rules for the British commonwealth nations reflect modern ideas about gender equality, Harris said, and the recognition that women who had become queens in the British monarch had held long and successful reigns.

"A lot of those queens that England has had have become iconic figures," Harris said. "The current queen is very popular as well. There's quite a positive association with female rulers in the United Kingdom."